PROJECT SUMMARY This proposal describes a five-year plan for Dr. Alireza Haghighi's career development towards becoming an independent cardiovascular investigator. Currently an Instructor in Medicine and Clinical Molecular Geneticist in Brigham and Women's Hospital (BWH), and Harvard Medical School (HMS), Dr. Haghighi's long-term career goals are to translate genomic research into clinical advances for cardiovascular patients. His career development and research plan leverages his training in human genetics and the unique training environment of BWH, HMS, and the Broad Institute that will provide him with new skills in statistics, computational biology, and induced pluripotent stem cell (iPSC) disease modeling, in order to shed novel insight into the mechanisms underlying hypertrophic cardiomyopathy (HCM). His career development goals will be achieved through scientific investigation and collaborations, and supported by mentorship, didactic coursework and conferences. Dr. Haghighi has assembled a Mentoring and Scientific Advisory Committee that includes world experts in cardiology, and human genetics: Drs. Christine Seidman (primary mentor), Jon Seidman (co-mentor), Shamil Sunyaev (advisor) and Mark Daly (advisor), who have mentored countless young investigators to successful independent investigators. HCM is the most common inherited cardiovascular diseases and the leading cause of sudden death in young people. Dominant mutations in sarcomere proteins cause HCM in 30-60% of patients- data that has enabled mechanistic studies that propel new therapeutic strategies to treat HCM. These opportunities are profoundly limited in sarcomere-negative (unexplained) HCM patients in whom there is no understanding of how or why disease emerges. Dr. Haghighi's whole exome sequencing (WES) analyses in genetically unexplained HCM patients concluded that non-coding variants may play a role in pathogenesis of this disease. This proposal seeks to define genetic etiologies (with a focus on non-coding variants) for HCM in patients that remain unsolved after WES sequencing by whole genome sequencing (WGS). To determine the functional impact of newly identified non-coding variants, Dr. Haghighi will model and characterize prioritized candidate variants in human isogenic cardiomyocytes derived from induced pluripotent stem cells (iPSC-CMs). Using these approaches he will explore three specific aims that (1) Identify rare variants in non-coding regions of known HCM genes and prioritized genes in blood and heart tissue samples of unexplained HCM patients by WGS, (2) Define dysregulated gene expressions and splicing effects of identified variants by RNAseq, and (3) Assess the effects of prioritized non-coding variants in human iPSCs. By providing fundamental new insights into the functional role of non-coding variants that may uncover new causes of HCM (thereby improving patient care), these studies will support NHLBI goals to improve our understanding of the molecular basis of health and disease. In addition, successful completion of the proposed studies advance Dr. Haghighi's transition to an independent clinical- scientist and provide him with a solid foundation from which he will apply for extramural funding.